1. Field of the Invention
The present invention pertains to an image viewing system that comprises an image display device that displays an image in front of a viewer's eyes while the device is either mounted on the viewer's head or held in front of the viewer's eyes, as well as a device that supplies the image to the image display device, and more particularly to an image viewing system that displays an image corresponding to the direction in which the viewer is looking.
2. Description of the Related Art
As an image viewing system, a system has been proposed that permits by means of a three-dimensional viewing device comprising, for example , a pair of left and right display units, viewing of an image shot by a three-dimensional camera system comprising a pair of left and right cameras. For example, in Japanese Laid Open Patent No. SHO 57-121487, an image display device mounted on the head (head mounted display, abbreviated as "HMD" below) changes the direction of image shooting of a three-dimensional camera system in accordance with the direction in which the viewer is looking. In these devices, because the direction of image shooting of the three-dimensional camera system is set in accordance with the detected direction of viewing, images may be viewed that are as realistic as if the viewer were present where the cameras are located.
However, where the direction of image shooting is set simply based on the viewing direction, if the object desired to be shot is located behind the viewer, for example, in order to look at it, the viewer must turn completely around. If the object is above the viewer, the viewer must look overhead, which, where the viewer desires to view the object for a long time, is uncomfortable and causes eyestrain and disorientation in the viewer.
Where the object is viewed in enlargement, because the focal length of the cameras' lens systems used for image shooting is set to a long focal length, the displayed image changes considerably in response to a slight change in the direction of image shooting that results from a change in the direction of viewing, which makes it difficult to set the direction of viewing. In addition, because even a slight change in the direction of viewing results in a substantial change in the displayed image, the problem occurs that the target object is lost from view.